Earphones, also referred to as in-ear monitors, canal phones and earpieces, are commonly used to listen to both recorded and live music. A typical recorded music application would involve plugging the earphone into a music player such as a CD player, flash or hard drive based MP3 player, home stereo, or similar device using the earphone's headphone jack. Alternately, the earphone can be wirelessly coupled to the music player. In a typical live music application, an on-stage musician wears the earphone in order to hear his or her own music during a performance.
Earphones are typically quite small and are worn just outside the ear canal. Prior art earphones use either one or more diaphragm-based drivers, one or more armature-based drivers, or a combination of both driver types. Broadly characterized, a diaphragm is a moving-coil speaker with a paper or mylar diaphragm. Since the cost to manufacture diaphragms is relatively low, they are widely used in many common audio products. In contrast to the diaphragm approach, an armature receiver utilizes a piston design. Due to the inherent cost of armature receivers, however, they are typically only found in hearing aids and high-end in-ear monitors.
Armature drivers, also referred to as balanced armatures, were originally developed by the hearing aid industry. This type of driver uses a magnetically balanced shaft or armature within a small, typically rectangular, enclosure. A single armature is capable of accurately reproducing low-frequency audio or high-frequency audio, but incapable of providing high-fidelity performance across all frequencies. To overcome this limitation, armature-based earphones often use two, or even three, armature drivers. In such multiple armature arrangements, a crossover network is used to divide the frequency spectrum into multiple regions, i.e., low and high or low, medium, and high. Separate armature drivers are then used for each region, individual armature drivers being optimized for each region. In contrast to the multi-driver approach often used with armature drivers, earpieces utilizing diaphragm drivers are typically limited to a single diaphragm due to the size of the diaphragm assembly. Unfortunately, as diaphragm-based monitors have significant frequency roll off above 4 kHz, an earpiece with a single diaphragm cannot achieve the desired upper frequency response while still providing an accurate low frequency response.
In addition to utilizing one or more high-fidelity drivers, professional-quality earphones are either custom molded or they use generic eartips, also referred to as sleeves. Eartips are typically fabricated from a soft, pliable material such as foam or silicon in order to achieve the desired snug fit within the user's ear canal. In use, the eartips isolate the user, thus insuring that the user can hear every nuance of the reproduced audio source by minimizing the audio interference caused by competing background noise.
Although sound isolating earphones meet the requirements of many users, for example professional musicians, some users prefer to be able to hear a degree of background sound. This preference may be for convenience, for example to hear the telephone while using the earphones, or for safety, for example to hear traffic and/or emergency vehicles while cycling. Currently users must select the type of earphone based on the intended use, or at least the primary intended use. As a result, either the user must buy multiple earphone sets to accommodate different uses, or suffer with varying performance inadequacies. The present invention is designed to overcome this problem.